Electric current balancing device

ABSTRACT

An electric current balancing device includes an inverting circuit having a driving unit and one or more transformers coupled together for outputting an electric current to a load device, a detecting circuit coupled to the inverting circuit for receiving and detecting an electric current of the load device and for stabilizing and sending a stabilized and calibrated electric current to the inverting circuit, and a balancing transformer device having a primary side coupled to the inverting circuit for receiving the calibrated electric current from the inverting circuit, and a secondary side coupled to the load device for comparing an electric current of the load device with the calibrated electric current from the inverting circuit and for controlling the load device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electric current balancing device,and more particularly to an electric current balancing device forcoupling to a multi-loaded electric facility and for comparing theelectric current of each load with a steady and calibrated or regulatedor standard electric current, and for providing a stable and balancingelectric current to suitably energize the loads of the multi-loadedelectric facility.

2. Description of the Prior Art

Typical multi-loaded electric facilities, such as the typical liquidcrystal display (LCD) light devices or display panels may comprisevarious kinds of discharge lamps, such as cold cathode fluorescent lamps(CCFL) as the backlight source for the display panels, and employnetwork to drive the discharge lamps.

In larger LCD display panels, a number of lamps or light tubes arerequired to be provided and installed for providing the requiredbrightness. When a number of lamps are installed in the larger LCDdisplay panels, a single transformer or driving or actuating circuit isnot so effective on performance to actuate or drive two or moredischarge lamps that are coupled parallel with each other.

For example, the impedances of the discharge lamps may be different fromeach other, and may seriously influence the flowing of the electricitythrough the discharge lamps; i.e., the electricity may not be evenlyflown through the discharge lamps, such that the discharge lamps may notbe suitably driven or actuated or energized.

When the electric current is less than the required amount, thedischarge lamps may not be suitably driven or actuated or energized tothe required brightness, and the brightness in different portions orareas of the larger LCD display panels may be different from each other,and may seriously decrease the uniformity of the display panel s.

On the contrary, when the electric current is greater than thepredetermined amount, the discharge lamps may be over-energized and theworking life of the discharge lamps may be greatly decreased. Inaddition, the characteristics of the discharge lamps may be changed anytime, such that the electricity may not be used to evenly energizevarious discharge lamps.

For example, the diameters of different discharge lamps may be differentfrom each other, the mercury densities and/or the electrodes ofdifferent discharge lamps may also be different from each other, thepressures of different discharge lamps may also be different from eachother, such that the impedances of the discharge lamps may be differentfrom each other, and such that different discharge lamps may not beevenly energized by the typical driving or actuating circuits, and suchthat the discharge lamps of the typical LCD display panels may normallygenerate flashes and/or flickers that people may not be easily consciousof and that may hurt people or may easily fatigue people or users.

For allowing the lamps or light tubes to be suitably driven by thetransformer or driving or actuating circuit, the applicant has developeda multi-lamp actuating facility for evenly and uniformly driving oractuating a number of light tubes or lamps of such as liquid crystaldisplay (LCD) light devices or display panels or other multi-loadedelectric facilities.

For example, U.S. Pat. No. 6,856,099 to Chen et al. discloses one oftypical multi-lamp actuating facilities arranged for allowing the lampsor light tubes to be suitably driven by the transformer or driving oractuating circuit. However, the light tubes or lamps may includedifferent characters, such as lengths, outer diameters, mercurydensities, pressures, electrode appliances, etc. which may affect theenergizing or operating of the light tubes or lamps, such that the lighttubes or lamps may not be actuated or operated in the best operatingmodes or status.

The present invention has arisen to mitigate and/or obviate theafore-described disadvantages of the conventional actuating devices formulti-loaded facilities.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide an electriccurrent balancing device for coupling to a multi-loaded electricfacility and for comparing the electric current of each load with asteady and calibrated or regulated or standard electric current, and forproviding a stable and balancing electric current to suitably energizethe loads of the multi-loaded electric facility.

In accordance with one aspect of the invention, there is provided anelectric current balancing device comprising a load device, an invertingcircuit including a driving unit and at least one transformer coupledtogether for outputting an electric current to the load device, adetecting circuit coupled to the inverting circuit, the detectingcircuit being provided for receiving and detecting an electric currentof the load device and for stabilizing and providing a stabilized andcalibrated electric current to the inverting circuit, and a balancingtransformer device including a primary side coupled to the invertingcircuit for receiving the calibrated electric current from the invertingcircuit, and including a secondary side coupled to the load device forcomparing an electric current of the load device with the calibratedelectric current from the inverting circuit and for controlling the loaddevice.

The balancing transformer device may be selectively coupled between theprimary side of the transformer and the driving unit of the invertingcircuit.

The load device may include one or more light devices, such as coldcathode fluorescent lamps, light tubes, light emitting diodes, or otherlight devices, or the load device may either be a single phase, a doublephase, or a multi-phase voltage regulator module (VRM).

The balancing transformer device may also include at least two coilscoupled together at the secondary side of the balancing transformerdevice for forming a twins structure, a triplet structure or the like.

Further objectives and advantages of the present invention will becomeapparent from a careful reading of the detailed description providedhereinbelow, with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan schematic view illustrating a general construction ofan electric current balancing device in accordance with the presentinvention;

FIG. 2 is a plan schematic view illustrating an application of theelectric current balancing device;

FIG. 3 is a plan schematic view similar to FIG. 2, illustrating anotherapplication of the electric current balancing device;

FIG. 4 is a plan schematic view similar to FIGS. 2-3, illustrating afurther application of the electric current balancing device;

FIG. 5 is a plan schematic view similar to FIGS. 2-4, illustrating astill further application of the electric current balancing device;

FIG. 6 is a plan schematic view similar to FIGS. 2-5, illustrating astill further application of the electric current balancing device;

FIG. 7 is a plan schematic view similar to FIGS. 2-6, illustrating astill further application of the electric current balancing device;

FIG. 8 is a plan schematic view similar to FIGS. 2-7, illustrating astill further application of the electric current balancing device;

FIG. 9 is a plan schematic view similar to FIGS. 2-8, illustrating astill further application of the electric current balancing device;

FIG. 10 is a plan schematic view similar to FIGS. 2-9, illustrating astill further application of the electric current balancing device;

FIG. 11 is a plan schematic view similar to FIGS. 2-10, illustrating astill further application of the electric current balancing device;

FIG. 12 is a plan schematic view similar to FIGS. 2-11, illustrating astill further application of the electric current balancing device;

FIG. 13 is a plan schematic view similar to FIGS. 2-12, illustrating astill further application of the electric current balancing device;

FIG. 14 is a plan schematic view similar to FIGS. 2-13, illustrating astill further application of the electric current balancing device;

FIG. 15 is a plan schematic view similar to FIGS. 2-14, illustrating astill further application of the electric current balancing device; and

FIG. 16 is a plan schematic view illustrating a general application ofthe electric circuit of the electric current balancing device as shownin FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, and initially to FIG. 1, an electric currentbalancing device in accordance with the present invention comprises aninverting circuit 10, a detecting circuit 20, and a balancingtransformer device 30 for coupling to a multi-loaded electric facilityor load device 80, such as an LCD display panel 80 which includes one ormore loads or load members, such as cold cathode fluorescent lamps,light tubes, light emitting diodes, or other light devices, multi-phaseDC-DC converters, etc., and for providing a stable and balancingelectric current to suitably energize the loads of the multi-loadedelectric facility or load device 80.

The inverting circuit 10 includes a power circuit or device or drivingunit 11 and one or more transformers T or 12 for coupling to and forproviding the electric power or current to energize the multi-loadedelectric facility or load device 80. The detecting circuit 20 is coupledto the input terminal of the inverting circuit 10 and coupled to adetecting point or low voltage side of the multi-loaded electricfacility or load device 80, for receiving and detecting the electriccurrent of the multi-loaded or load device 80 and then, feedbacks to theinput terminal of the inverting circuit 10 for stabilizing and forproviding a stable electric power or current to energize themulti-loaded or load device 80.

The transformer T or 12 includes a primary side 13 coupled to thedriving unit 11, and a secondary side 14 coupled to the multi-loaded orload device 80 and the balancing transformer device 30. The balancingtransformer device 30 includes a primary side 31 coupled to outputterminal or the transformer T or 12 of the inverting circuit 10 forreceiving the stabilized electric power or current from the invertingcircuit 10, and includes a secondary side 32 coupled to the multi-loadedor load device 80 for suitably energizing or actuating the loads or loadmembers of the load device 80.

In accordance with Maxwell-Faraday's and Maxwell-Ampere's Lows onElectro-Magnetic Power Conversion, we have∇× E=31 {dot over (B)} & ∇× H= J+ {dot over (D)}in which E: electric field strength or intensity,

-   -   B: magnetic flux strength or intensity,    -   H: magnetic field strength or intensity,    -   J: electric current frnsity,    -   D: electric flux strength or intensity.

For a stationary closed path C, we have {dot over (D)}=0=>∇× H= J, andby Stokes' theorem for space vector analysis, it shows:∫_(A) ∇× A·d s=∫ _(C) A·d l=>∫_(A) ∇× E·d s=∫ _(C) E·d l=−∫ _(A) {dot over (B)}·d s &∫_(A) ∇× H·d s=∫ _(C) H·d l=∫ _(A) J·d s

In the present electric current balancing device, a ferrite core of anisotropic characteristic is used, and we get the electromotive force(emf) and the magneto-motive force (mmf) as below:emf=V=∫ _(C) E·d l=∫ _(A) ∇× E·d s=−∫ _(A) {dot over (B)}·ds=−nAdB/dt=−ndφ/dt, and mmf=Hl=∫ _(C) H·d l=∫ _(A) ∇× H·d s=∫ _(A) J·ds=Σni=>H=Σni/l, and B=μH=μΣni/l

So we haveV _(s) =−n _(s) AdB/dt=−n _(s) Ad(μΣni/l)/dt=−(μn_(s) A/l)d(n _(s) i_(s) −n _(p) i _(p))/dtand in the present electric current balancing device, i_(p) is fixed orhas been calibrated into stable current, such thatV _(s)=−(μn_(s) A/l)d(n _(s) i _(s))/dt=−μn _(s) ² A/l·di _(s) /dt=−L_(s) di _(s) /dtin which φ: magnetic flux in the ferrite core,

-   -   L: inductance,    -   μ: magnetic permeability.

Accordingly, in case of any unbalance of current existed between thesecondary side 32 and the primary side 31 of the balancing transformerdevice 30, a back emf of V_(s) is going to be induced in proportional tothe variation of secondary side current (di_(s)/dt) and is amplifiedalso by the secondary inductance (L_(s)), and is applied upon the loaddevice 80 that is coupled to the secondary side 32 of the balancingtransformer device 30, the electric current in the secondary side 32 ofthe balancing transformer device 30 may thus be enforces or balanced orcorrected and will then be equally matched with that in the primary side31 of the balancing transformer device 30.

When balanced: (i.e., n_(s)i_(s)=n_(p)i_(p))=>H=n _(s) i _(s) −n _(p) i _(p)=0 & B=μH=0=>V_(s)=0

The balancing device will thus work like a simple electric currenttransformer only, and the electric current conducted at each side of thebalancing transformer device 30 shall be exactly inverse proportional toits turn ratio, and there will be no back emf induced and imposed on anyside of the balancing transformer device 30 and/or the multi-loadedelectric facility or load device 80.

When unbalanced: (i.e., n_(s)i_(s)≠n_(p)i_(p))=>V _(s) =−L _(s) di _(s) /dt

That is, once there's any unbalance condition happened, no mater it iscaused by the variation of load or the voltage source, a transientcorrective force of back emf=V_(s)=−L_(s)di_(s)/dt will be induced onthe secondary side 32 of the balancing transformer device 30 and theelectric current at the secondary side 32 of the balancing transformerdevice 30 will be adjusted according, until reaching the balancecondition: n_(s)i_(s)=n_(p)i_(p).

Accordingly, as shown in FIG. 1, when the electric current balancingdevice is operated, the detecting circuit 20 may receive and detect theelectric current (io) from the multi-loaded electric facility or loaddevice 80 and may stabilize the electric current and then feed theelectric current back to the input terminal of the inverting circuit 10,for allowing the electric current balancing device to output acalibrated and stabilized electric current to the balancing transformerdevice 30 and then to the multi-loaded electric facility or load device80.

Under the application of Lenz's Law, when the electric current at thesecondary side 32 of the balancing transformer device 30 or at orthrough the load device 80 is varied or changed, a back emf will beinduced or generated on the secondary side 32 of the balancingtransformer device 30 or at the load device 80 and will be compared ormatched with the calibrated or stabilized electric current at theprimary side 31 of the balancing transformer device 30, in order toavoid or to prevent the electric current at the secondary side 32 of thebalancing transformer device 30 or at the load device 80 from beingvaried or changed, and thus for allowing the load device 80 to be stablyworked or energized by the calibrated or stabilized electric current.

Referring next to FIGS. 2-7, illustrated are various applications of theelectric current balancing device, in which the balancing transformermembers CBk of the balancing transformer device 30 are indicated orrepresented by CB1, CB2, . . . CBk, the winding turns in the primaryside 31 and the secondary side 32 of the balancing transformer device 30are indicated or represented by nk1 and nk2 respectively, the electriccurrent is indicated or represented by ik, the capacitor is indicated orrepresented by Ck, the conventional balancing transformer members of orin the load device 80 is indicated or represented by BTk, and the loadmembers of the load device 80 is indicated or represented by Loadk.

For example, in FIGS. 2-7, the balancing transformer device 30 may becoupled to the secondary side 14 of the transformer T or 12 of theinverting circuit 10, and the balancing transformer members CBk of thebalancing transformer device 30 are arranged or coupled in parallel toeach other and coupled to the high voltage side of the load device 80(FIGS. 2-6) or coupled to the low voltage side of the load device 80(FIG. 7), for allowing the output calibrated and stabilized electriccurrent from the inverting circuit 10 to evenly flow to the load membersLoadk of the load device 80, in order to suitably control and balancethe electric current supplied to the load members Loadk of the loaddevice 80.

In FIGS. 2 and 6, the capacitors Ck are the ballast capacitors forcoupling to the load members Loadk of the load device 80 respectivelyand for sharing and distributing the voltage and for v stabilizing theelectric current and thus for indirectly driving the load members Loadkof the load device 80 respectively. When the load members Loadk of theload device 80 are arranged to be directly driven by the output of thetransformer T or 12 of the inverter circuit 10 and/or the balancingtransformer device 30, then the ballast capacitors Ck may be deleted,and then the electric circuits in FIGS. 2 and 6 will be the same or theidentical electric circuit.

As shown in FIG. 3, when larger or longer lamps or light tubes are used,higher voltage or higher load will be required, and the invertingcircuit 10 is required to provide two transformers 12 or T1 and T2 andto couple the two transformers T1 and T2 in series, in order to providean increased working voltage, and thus to avoid or to prevent the arcingphenomena from being generated. At this moment, the load members Loadkof the load device 80 are floating, and the coupling or connectedportion of the two transformers T1 and T2 is grounded, such that theload members Loadk of the load device 80 are also taken as virtualgrounding, and such that the voltage for the load members Loadk of theload device 80 will be decreased by one half, and such that the electriccurrent supplied to the load members Loadk of the load device 80 may besuitably controlled and balanced.

As shown in FIGS. 4 and 5, two (FIG. 4) or more load members Loadk (FIG.5) may be selectively coupled to each of the balancing transformermembers CBk of the balancing transformer device 30, for forming a twinsstructure, a triplet structure or the like, and for allowing theelectric current supplied to the load members Loadk of the load device80 to be suitably controlled and balanced.

As shown in FIG. 8, the balancing transformer device 30 may be coupledto the primary side 13 of the transformer T or 12 of the invertingcircuit 10, and may be coupled in seriea to the transformer T or 12 ofthe inverting circuit 10 and the driving unit 11 of the invertingcircuit 10, for allowing the stabilized and balanced electric currentsupplied from the inverting circuit 10 to evenly flow to the loadmembers Loadk of the load device 80 and to suitably control and balancethe load members Loadk of the load device 80.

As shown in FIG. 9, the balancing transformer device 30 may also becoupled to the primary side 13 of the transformer T or 12 of theinverting circuit 10, and may be coupled in tree type structure to thetransformer T or 12 of the inverting circuit 10 and the driving unit 11of the inverting circuit 10, for allowing the stabilized and balancedelectric current supplied from the inverting circuit 10 to evenly flowto the load members Loadk of the load device 80 and to suitably controland balance the load members Loadk of the load device 80.

As shown in FIGS. 10 and 11, the balancing transformer device 30 mayalso be coupled to the primary side 13 of the transformer T or 12 of theinverting circuit 10, and may be coupled in series to the transformer Tor 12 of the inverting circuit 10 and the driving unit 11 of theinverting circuit 10, and the conventional balancing transformer membersTBk may further be provided and coupled to the high voltage side of theload device 80 (FIG. 10) or coupled to the low voltage side of the loaddevice 80 (FIG. 11), for allowing the stabilized and balanced electriccurrent to be supplied from the inverting circuit 10 to evenly flow tothe load members Loadk of the load device 80 and to suitably control andbalance the load members Loadk of the load device 80.

As shown in FIGS. 12 and 13, the balancing transformer device 30 mayalso be coupled to the primary side 13 of the transformer T or 12 of theinverting circuit 10 which includes two secondary windings and outputterminals, and the conventional balancing transformer members TBk mayfurther be provided and coupled to the high voltage side of the loaddevice 80 (FIG. 12) or coupled to the low voltage side of the loaddevice 80 (FIG. 13), for allowing the stabilized and balanced electriccurrent supplied from the inverting circuit 10 to evenly flow to theload members Loadk of the load device 80 via the double output terminalsof the transformer T or 12 of the inverting circuit 10, and to suitablycontrol and balance the load members Loadk of the load device 80.

As shown in FIG. 14, the load members Loadk of the load device 80 may bethe light emitting diodes or the like, the balancing transformer device30 may be coupled to the secondary side 14 of the transformer T or 12 ofthe inverting circuit 10, and coupled in parallel to each other andcoupled to either the low voltage side or the high voltage side of theload device 80, for allowing the stabilized and balanced electriccurrent supplied from the inverting circuit 10 to evenly flow to theload members Loadk of the load device 80 and to suitably control andbalance the load members Loadk of the load device 80, in addition, evenwhen the light emitting diodes or the other lighting members are aged,the turn ratio of the primary side 31 and the secondary side 32 of thebalancing transformer device 30 may be regulated for allowing thelighting members of different brightness to generate the requiredbrightness and color rendering or color temperature.

As shown in FIGS. 15 and 16, the balancing transformer device 30 may beused or coupled in various single phase, double phase, or multi-phasevoltage regulator modules (VRMs), and may be coupled between a switchingunit 16 of the inverting circuit 10 and a distributing inductor 50 forallowing the electric current supplied from the inverting circuit 10 toevenly flow to the inductor members Lk of the distributing inductor 50and thus for allowing the heat source of the whole module to be evenlydistributed. As shown in FIG. 16, the balancing transformer device 30and the distributing inductor 50 may be coupled and constructed togetherin a dual in one core-and-coil structure, and a differential modecoupling effect Lc between the primary side 31 and the secondary side 32of the balancing transformer device 30 may be used for balancing thebalancing transformer device 30, and the leakage inductance Lk may beapplied to and worked as the distributing inductor 50 for evenly oruniformly distributing purposes.

Accordingly, the balancing transformer device 30 may compare theelectric current of each of the load members Loadk of the load device 80with a calibrated and stabilized electric current, in order to suitablycontrol and balance the load members Loadk of the load device 80, and soas to control the driving or energizing or lighting of the load membersLoadk of the load device 80. The load members Loadk of the load device80 may thus be suitably controlled or operated or driven without beingaffected by the characters of the load members Loadk of the load device80.

Accordingly, the electric current balancing device in accordance withthe present invention may be provided for coupling to a multi-loadedelectric facility and for comparing the electric current of each loadwith a steady and calibrated or regulated or standard electric current,and for providing a stable and balancing electric current to suitablyenergize the loads of the multi-loaded electric facility.

Although this invention has been described with a certain degree ofparticularity, it is to be understood that the present disclosure hasbeen made by way of example only and that numerous changes in thedetailed construction and the combination and arrangement of parts maybe resorted to without departing from the spirit and scope of theinvention as hereinafter claimed.

1. An electric current balancing device comprising: a load device, aninverting circuit including a driving unit and at least one transformercoupled together for outputting an electric current to said load device,a detecting circuit coupled to said inverting circuit, said detectingcircuit being provided for receiving and detecting an electric currentof said load device and for stabilizing and providing a stabilized andcalibrated electric current to said inverting circuit, and a balancingtransformer device including a primary side coupled to said invertingcircuit for receiving the calibrated electric current from saidinverting circuit, and including a secondary side coupled to saidprimary side of said balancing transformer device and then coupled tosaid load device for comparing an electric current of said load devicewith the calibrated electric current from said inverting circuit and forcontrolling said load device.
 2. The electric current balancing deviceas claimed in claim 1, wherein said balancing transformer device isselectively coupled between a primary side of said at least onetransformer and said driving unit of said inverting circuit.
 3. Theelectric current balancing device as claimed in claim 1, wherein saidbalancing transformer device includes at least two coils coupledtogether at said secondary side of said balancing transformer device. 4.The electric current balancing device as claimed in claim 1, whereinsaid load device includes at least one light device.
 5. The electriccurrent balancing device as claimed in claim 1, wherein said load deviceis either a single phase, a double phase, or a multi-phase voltageregulator module.